Yellow-throated Warbler (Dendroica dominica)
Tewinkle Park, Costa Mesa, Orange County, California
25 January 2007
Joseph Morlan

Photos © 25 January 2007 by Jim Pike. All rights reserved.
Today, Dan Singer, Robbie Fischer and I joined Jim Pike to look for some known stake-out rarities in Orange County. Shortly after noon we visited Tewinkle Park in Costa Mesa to look for the Yellow-throated Warbler which was known to be wintering in the area. About 12:30pm Jim found the bird foraging in an isolated conifer near the edge of the park. The bird remained to forage on the bark of the tree limbs before moving to a different conifer where it buried itself in a clump on needles where it preened. Jim and Dan took photos of the bird and some of Jim's are reproduced here by permission.

Description

This was a medium-sized warbler which foraged alone, not joining the flocks of Yellow-rumped Warblers which moved through the park. It foraged much like a nuthatch or Black-and-white Warbler, by creeping along the tree trunk and limbs, probing into the bark with its long, thin slightly curved bill. Its upperparts were neutral gray with a slight brownish tinge in some lighting conditions and some darkening towards the forehead. Its dark eye was bordered above with a white supercilium. Above a dark lore stripe, the supraloral area looked white most of the time, but occasionally showed a tinge of yellow depending on light and angle (cf. photo left). Below the eye was a dark wedge-shaped cheek patch which was bordered towards the rear by a crescent-shaped white patch. Gray extended from the eye, back connecting with the nape and separating the white supercilium from the white post auricular crescent. The wings were gray with two bold white wing bars formed by white tips to the greater and median coverts.

The throat and breast were a bright butter-yellow coloration, becoming paler, almost whitish in the chin. The rest of the underparts were white with some black streaking on the sides of the breast extending to more diffuse streaks on the flanks. The underside of the tail was mostly white with minimal dark at the base of the tail spots (cf. photo right). The bird was silent.

Discussion

This individual has been present in the area since 12 November 2006 when first found by Doug Willick and Jim Pike. Although males and females are similar in this species, females average duller with more buff on the flanks. This bird seems to be somewhat ambiguous in these features and I do not feel qualified to judge its sex.

While the species identification is straightforward, the subspecies is not. The large-billed, yellow-lored race, D. d. dominica, breeds in pines along the East Coast while short-billed, white-lored D. d. albilora breeds in Sycamores throughout the Midwest. D. d. stoddardi is localized in the Florida panhandle and adjacent Alabama and is weakly differentiated from D. d. dominica. Another subspecies is resident in the Bahamas. Nominate birds winter from South Carolina south to the West Indies while albilora winters mainly from southern Texas to Mexico and Middle America. The vast majority of the nearly 100 records of Yellow-throated Warbler in California have been identified or suspected of being albilora and these are mostly from Spring and Fall with a few in Summer. There are at least five previous California records of birds thought to be D. d. dominica as follows:

Although nominate dominica averages a longer bill than albilora, there is overlap in bill measurements. Lore color is also unreliable with many albilora showing a tinge of yellow in the lores and some dominica evidently lacking yellow. Past records suggest that wintering birds are more likely to be dominica, but it is probably unwise to assign a definite subspecies name when the characters are so variable and, in this case, seem so ambiguous.

References

Craig, J.T. 1972. Two fall Yellow-throated Warblers in California. Calif. Birds 3:17-18.
Dunn, J. L., and K. L. Garrett. 1997. A Field Guide to Warblers of North America. Houghton Mifflin, New York.
Garrett, K. L., and D. S. Singer. 1998. Annual report of the California Bird Records Committee: 1995 records. W. Birds 29:133-156.
Jaramillo A. 1993. Subspecific identification of Yellow-throated Warblers. Birders' J. 2:160.